1. Field
This invention relates to methods and systems for detecting a fault in an oil and gas apparatus controlled by a controller.
2. Description of the Related Art
A controller may control one or more physical system components to achieve a set of common objectives. The controller may be designed to reliably control the physical system components in the presence of external disturbances, variations among physical components due to manufacturing tolerances, and changes in commanded input values for controlled output values, such as, for example, drilling fluid density, cement mixture density, and other fluid properties. The controller may also be designed to remain stable and avoid oscillations within a range of specific operating conditions.
In a wellbore environment, the controller may be used to control a physical system component such as an oil and gas apparatus used for mixing materials to achieve a desired mixture output or for providing the mixture downhole. For example, when drilling an oil or gas well, it is common to install a tubular casing into the wellbore, mix materials to make a cement mix, and pump the cement mix into place cementing the casing in place against the wellbore wall. In another embodiment, the controller may be used to control an oil and gas apparatus used for providing drilling fluid when drilling an oil or gas well. For example, the controller is used to control oil and gas apparatuses that mix materials to make the drilling fluid and pump the drilling fluid which is sometimes called a drilling mud. The drilling fluid provides hydrostatic pressure to prevent formation fluids from entering into the wellbore, keeps a drill bit cool and clean during drilling, carries out drill cuttings, and suspends the drill cuttings while drilling is paused and when the drilling assembly is brought in and out of the hole.
Oil and gas processing equipment that supports wellbore servicing operations, such as cementing or drilling, may be designed to work with the controller configured to provide a desired volumetric flow rate of mixed cement or drilling fluid having desired properties such as density, pressure, and flow rate. In particular, in the case of cementing, a controller may control oil and gas apparatuses such as valves that allow the in-flow of dry cement material and water to obtain the desired cement mixture density and desired cement mixture volumetric flow rate. The controller may operate, by monitoring the cement mixture flow rate and density, and by regulating an in-flow water valve and an in-flow dry cement material valve. Further, in the case of drilling, a controller may control oil and gas apparatuses such as valves that allow the in-flow of drilling fluid components and water to obtain the desired drilling fluid density and desired drilling fluid volumetric flow rate. The controller may operate, for example, by monitoring the drilling fluid flow rate and density, and by regulating an in-flow water valve and an in-flow drilling fluid component valve. During cementing or drilling, a fault in an oil and gas apparatus may occur which may be detected by the controller allowing for corrective measures to be determined and implemented.
Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience.